The present invention relates to a red brick and a method for manufacturing the same, and more particularly, to a red brick formed primarily of waste foundry sand discharged from a foundry and dusts discharged from a steel factory, and to a method for manufacturing the same.
The main ingredients of a red brick are clay and sand. The sand is used for preventing contraction and cracks of the bricks and maintaining the strength of the same. However, efforts to reduce the quantity of sand used for manufacturing the red bricks or to search for a substitute for the sand are necessary since sand is in continuously increasing in demand and the supply is being exhausted.
The waste foundry sand is about 9.about.10 in a pH level and contains SiO.sub.2 (about 97%) as a main component and Al.sub.2 O.sub.3 and Fe.sub.2 O.sub.3, etc, as other small amount components. However, the waste foundry sand contains materials such as Pb, Cu, Cd, As and Cr, etc, which are undesirable or harmful components. It is not easy to eliminate those harmful components. Also, if elimination cost of the undesirable components of the waste foundry sand exceeds a certain level, the economical efficiency of manufacturing industries which use the waste foundry sand is considerably lowered.
At present, most waste foundry sand is disposed of by being buried, which causes a serious shortage in burial land. Specific waste foundry sand containing harmful components such as Pb and Cu, etc, must be disposed under the relevant waste disposal laws in order to prevent an environmental pollution caused by heavy metals. Otherwise, general waste foundry sand which does not include the heavy metals must be recycled without being buried. However, there is no desirable way for utilizing the general waste foundry sand.
Also, one of the industrial wastes discharged in large quantities is the dusts discharged from a steel factory. The main components of these dusts are Fe, C, and limestone, etc. The recycling rate of these dusts is very low at present, and it is difficult to secure burial land as in the case of waste foundry sand. Research study into an application method of recycled products which can be manufactured at a low cost without causing environmental pollution is keenly necessary due to a secondarily caused pollution and excessive processing costs, even though the dusts are recycled.
Meanwhile, in conventional processing for manufacturing red brick, a heating temperature should be raised up to 1300.degree. C. In this case, the economical efficiency of the manufacturing processing is very poor since about 13 hours at that temperature are needed and about 240 liters of fuel oil is consumed to raise that temperature, and about 25 hours are needed to cool the bricks. A reduction process is generally performed in order to make the bricks exhibit a desirable color. Since installation for the reduction process is very complicated and the costs for manufacturing the red bricks are very high, the economical efficiency of the red brick manufacturing industry is very poor.